This thesis is based on two assumptions. Firstly, it is assumed that there is a significant difference regarding the performing level of year 9 students attending private and public schools in the vicinity of Berlin, affecting subjects such as mathematics, informatics, science and technology. This theory can be proven with the results of a survey which had been carried out earlier. Secondly, it is assumed that there is a distinction between the student’s socioeconomic background in private and public schools. Other than previous studies, this examination solely focuses on schools in one federal state. As a result confounders such as the number of lessons, curriculum and assessment criteria can be avoided as these factors are uniform in the area surrounding Berlin. Previous studies, carried out in more than one federal state, have failed to be based on the same preconditions ever since. Collected data will be analyzed using a comparison of means, analysis of variance and partial correlation. Both, possible reasons in performance disparities, as well as disparities reflected in the socioeconomic background of the students will be discussed in this thesis.